This invention relates to an apparatus and a method for aligning tubulars.
During the construction, maintenance and repair of oil and gas wells it is necessary to connect a large number of tubulars, for example lengths of drill pipe and casing. Conventionally the upper end of a tubular is provided with a threaded socket whilst the lower end is provided with a threaded pin which is slightly tapered.
In practice it is very easy for the pin of one tubular to be incorrectly inserted into the socket of an adjacent tubular with the result that the threads on one or both the pin and the socket can readily be damaged.
Considerable skill is required to correctly align tubulars and historically this task has been undertaken by a highly experienced rig-hand called a xe2x80x9cstabberxe2x80x9d.
In order to facilitate correct alignment a device known as a xe2x80x9cstabbing guidexe2x80x9d is frequently used. One such stabbing guide comprises a plastic body member which can be mounted on the socket of a pipe held in slips. The plastic body member has a central passageway the upper part of which defines a funnel which leads into a lower passageway which is concentric with the socket. In use, as the upper tubular is lowered, its pin enters the funnel of the stabbing guide and then travels down the lower passageway into the socket. The stabbing guide (which comprises two semi-circular pieces hinged together around the socket) is then removed and the tubulars are screwed together and tightened to the required torque either by a power tong or a tong assembly comprising a power tong and a backup tong.
In order to simplify the stabbing operation the present invention provides an apparatus for aligning tubulars which apparatus comprises a guide mounted on one of a power tong and a backup tong.
In one embodiment said apparatus further comprises a socket centralizer mounted on said one of said power tong and said backup tong.
Preferably, said one of said power tong and said backup tong is said power tong.
In another embodiment, said apparatus comprises a power tong and a backup tong, wherein said guide is mounted on said power tong and means are provided to maintain said power tong and said backup tong in a certain juxtaposition during a stabbing operation.
Preferably, said means comprises locating rods on one of said power tong and said backup tong and blocks shaped to receive at least the ends of said locating rods on the other of said power tong and said backup tong.
Advantageously, said backup tong is provided with at least two prismatic jaw assemblies to locate said backup tong in fixed juxtaposition with respect to a tubular being gripped.
The present invention also provides methods for aligning tubulars as set out in claims 7 and 8 hereto.